// Copyright 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


// Known Issues:
//
// * Patterns are not implemented.
// * Radial gradient are not implemented. The VML version of these look very
//   different from the canvas one.
// * Clipping paths are not implemented.
// * Coordsize. The width and height attribute have higher priority than the
//   width and height style values which isn't correct.
// * Painting mode isn't implemented.
// * Canvas width/height should is using content-box by default. IE in
//   Quirks mode will draw the canvas using border-box. Either change your
//   doctype to HTML5
//   (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
//   or use Box Sizing Behavior from WebFX
//   (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
// * Non uniform scaling does not correctly scale strokes.
// * Optimize. There is always room for speed improvements.

// Only add this code if we do not already have a canvas implementation
if (!document.createElement('canvas').getContext) {

	(function() {

		// alias some functions to make (compiled) code shorter
		var m = Math;
		var mr = m.round;
		var ms = m.sin;
		var mc = m.cos;
		var abs = m.abs;
		var sqrt = m.sqrt;

		// this is used for sub pixel precision
		var Z = 10;
		var Z2 = Z / 2;

		/**
		 * This funtion is assigned to the <canvas> elements as element.getContext().
		 * @this {HTMLElement}
		 * @return {CanvasRenderingContext2D_}
		 */
		function getContext() {
			return this.context_ ||
				   (this.context_ = new CanvasRenderingContext2D_(this));
		}

		var slice = Array.prototype.slice;

		/**
		 * Binds a function to an object. The returned function will always use the
		 * passed in {@code obj} as {@code this}.
		 *
		 * Example:
		 *
		 *   g = bind(f, obj, a, b)
		 *   g(c, d) // will do f.call(obj, a, b, c, d)
		 *
		 * @param {Function} f The function to bind the object to
		 * @param {Object} obj The object that should act as this when the function
		 *	 is called
		 * @param {*} var_args Rest arguments that will be used as the initial
		 *	 arguments when the function is called
		 * @return {Function} A new function that has bound this
		 */
		function bind(f, obj, var_args) {
			var a = slice.call(arguments, 2);
			return function() {
				return f.apply(obj, a.concat(slice.call(arguments)));
			};
		}

		var G_vmlCanvasManager_ = {
			init: function(opt_doc) {
				if (/MSIE/.test(navigator.userAgent) && !window.opera) {
					var doc = opt_doc || document;
					// Create a dummy element so that IE will allow canvas elements to be
					// recognized.
					doc.createElement('canvas');
					doc.attachEvent('onreadystatechange', bind(this.init_, this, doc));
				}
			},

			init_: function(doc) {
				// create xmlns
				if (!doc.namespaces['g_vml_']) {
					doc.namespaces.add('g_vml_', 'urn:schemas-microsoft-com:vml',
									   '#default#VML');

				}
				if (!doc.namespaces['g_o_']) {
					doc.namespaces.add('g_o_', 'urn:schemas-microsoft-com:office:office',
									   '#default#VML');
				}

				// Setup default CSS.  Only add one style sheet per document
				if (!doc.styleSheets['ex_canvas_']) {
					var ss = doc.createStyleSheet();
					ss.owningElement.id = 'ex_canvas_';
					ss.cssText = 'canvas{display:inline-block;overflow:hidden;' +
									 // default size is 300x150 in Gecko and Opera
								 'text-align:left;width:300px;height:150px}' +
								 'g_vml_\\:*{behavior:url(#default#VML)}' +
								 'g_o_\\:*{behavior:url(#default#VML)}';

				}

				// find all canvas elements
				var els = doc.getElementsByTagName('canvas');
				for (var i = 0; i < els.length; i++) {
					this.initElement(els[i]);
				}
			},

			/**
			 * Public initializes a canvas element so that it can be used as canvas
			 * element from now on. This is called automatically before the page is
			 * loaded but if you are creating elements using createElement you need to
			 * make sure this is called on the element.
			 * @param {HTMLElement} el The canvas element to initialize.
			 * @return {HTMLElement} the element that was created.
			 */
			initElement: function(el) {
				if (!el.getContext) {

					el.getContext = getContext;

					// Remove fallback content. There is no way to hide text nodes so we
					// just remove all childNodes. We could hide all elements and remove
					// text nodes but who really cares about the fallback content.
					el.innerHTML = '';

					// do not use inline function because that will leak memory
					el.attachEvent('onpropertychange', onPropertyChange);
					el.attachEvent('onresize', onResize);

					var attrs = el.attributes;
					if (attrs.width && attrs.width.specified) {
						// TODO: use runtimeStyle and coordsize
						// el.getContext().setWidth_(attrs.width.nodeValue);
						el.style.width = attrs.width.nodeValue + 'px';
					} else {
						el.width = el.clientWidth;
					}
					if (attrs.height && attrs.height.specified) {
						// TODO: use runtimeStyle and coordsize
						// el.getContext().setHeight_(attrs.height.nodeValue);
						el.style.height = attrs.height.nodeValue + 'px';
					} else {
						el.height = el.clientHeight;
					}
					//el.getContext().setCoordsize_()
				}
				return el;
			}
		};

		function onPropertyChange(e) {
			var el = e.srcElement;

			switch (e.propertyName) {
				case 'width':
					el.style.width = el.attributes.width.nodeValue + 'px';
					el.getContext().clearRect();
					break;
				case 'height':
					el.style.height = el.attributes.height.nodeValue + 'px';
					el.getContext().clearRect();
					break;
			}
		}

		function onResize(e) {
			var el = e.srcElement;
			if (el.firstChild) {
				el.firstChild.style.width = el.clientWidth + 'px';
				el.firstChild.style.height = el.clientHeight + 'px';
			}
		}

		G_vmlCanvasManager_.init();

		// precompute "00" to "FF"
		var dec2hex = [];
		for (var i = 0; i < 16; i++) {
			for (var j = 0; j < 16; j++) {
				dec2hex[i * 16 + j] = i.toString(16) + j.toString(16);
			}
		}

		function createMatrixIdentity() {
			return [
				[1, 0, 0],
				[0, 1, 0],
				[0, 0, 1]
			];
		}

		function matrixMultiply(m1, m2) {
			var result = createMatrixIdentity();

			for (var x = 0; x < 3; x++) {
				for (var y = 0; y < 3; y++) {
					var sum = 0;

					for (var z = 0; z < 3; z++) {
						sum += m1[x][z] * m2[z][y];
					}

					result[x][y] = sum;
				}
			}
			return result;
		}

		function copyState(o1, o2) {
			o2.fillStyle = o1.fillStyle;
			o2.lineCap = o1.lineCap;
			o2.lineJoin = o1.lineJoin;
			o2.lineWidth = o1.lineWidth;
			o2.miterLimit = o1.miterLimit;
			o2.shadowBlur = o1.shadowBlur;
			o2.shadowColor = o1.shadowColor;
			o2.shadowOffsetX = o1.shadowOffsetX;
			o2.shadowOffsetY = o1.shadowOffsetY;
			o2.strokeStyle = o1.strokeStyle;
			o2.globalAlpha = o1.globalAlpha;
			o2.arcScaleX_ = o1.arcScaleX_;
			o2.arcScaleY_ = o1.arcScaleY_;
			o2.lineScale_ = o1.lineScale_;
		}

		function processStyle(styleString) {
			var str, alpha = 1;

			styleString = String(styleString);
			if (styleString.substring(0, 3) == 'rgb') {
				var start = styleString.indexOf('(', 3);
				var end = styleString.indexOf(')', start + 1);
				var guts = styleString.substring(start + 1, end).split(',');

				str = '#';
				for (var i = 0; i < 3; i++) {
					str += dec2hex[Number(guts[i])];
				}

				if (guts.length == 4 && styleString.substr(3, 1) == 'a') {
					alpha = guts[3];
				}
			} else {
				str = styleString;
			}

			return {color: str, alpha: alpha};
		}

		function processLineCap(lineCap) {
			switch (lineCap) {
				case 'butt':
					return 'flat';
				case 'round':
					return 'round';
				case 'square':
				default:
					return 'square';
			}
		}

		/**
		 * This class implements CanvasRenderingContext2D interface as described by
		 * the WHATWG.
		 * @param {HTMLElement} surfaceElement The element that the 2D context should
		 * be associated with
		 */
		function CanvasRenderingContext2D_(surfaceElement) {
			this.m_ = createMatrixIdentity();

			this.mStack_ = [];
			this.aStack_ = [];
			this.currentPath_ = [];

			// Canvas context properties
			this.strokeStyle = '#000';
			this.fillStyle = '#000';

			this.lineWidth = 1;
			this.lineJoin = 'miter';
			this.lineCap = 'butt';
			this.miterLimit = Z * 1;
			this.globalAlpha = 1;
			this.canvas = surfaceElement;

			var el = surfaceElement.ownerDocument.createElement('div');
			el.style.width = surfaceElement.clientWidth + 'px';
			el.style.height = surfaceElement.clientHeight + 'px';
			el.style.overflow = 'hidden';
			el.style.position = 'absolute';
			surfaceElement.appendChild(el);

			this.element_ = el;
			this.arcScaleX_ = 1;
			this.arcScaleY_ = 1;
			this.lineScale_ = 1;
		}

		var contextPrototype = CanvasRenderingContext2D_.prototype;
		contextPrototype.clearRect = function() {
			this.element_.innerHTML = '';
		};

		contextPrototype.beginPath = function() {
			// TODO: Branch current matrix so that save/restore has no effect
			//       as per safari docs.
			this.currentPath_ = [];
		};

		contextPrototype.moveTo = function(aX, aY) {
			var p = this.getCoords_(aX, aY);
			this.currentPath_.push({type: 'moveTo', x: p.x, y: p.y});
			this.currentX_ = p.x;
			this.currentY_ = p.y;
		};

		contextPrototype.lineTo = function(aX, aY) {
			var p = this.getCoords_(aX, aY);
			this.currentPath_.push({type: 'lineTo', x: p.x, y: p.y});

			this.currentX_ = p.x;
			this.currentY_ = p.y;
		};

		contextPrototype.bezierCurveTo = function(aCP1x, aCP1y, aCP2x, aCP2y, aX, aY) {
			var p = this.getCoords_(aX, aY);
			var cp1 = this.getCoords_(aCP1x, aCP1y);
			var cp2 = this.getCoords_(aCP2x, aCP2y);
			bezierCurveTo(this, cp1, cp2, p);
		};

		// Helper function that takes the already fixed cordinates.
		function bezierCurveTo(self, cp1, cp2, p) {
			self.currentPath_.push({
									   type: 'bezierCurveTo',
									   cp1x: cp1.x,
									   cp1y: cp1.y,
									   cp2x: cp2.x,
									   cp2y: cp2.y,
									   x: p.x,
									   y: p.y
								   });
			self.currentX_ = p.x;
			self.currentY_ = p.y;
		}

		contextPrototype.quadraticCurveTo = function(aCPx, aCPy, aX, aY) {
			// the following is lifted almost directly from
			// http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes

			var cp = this.getCoords_(aCPx, aCPy);
			var p = this.getCoords_(aX, aY);

			var cp1 = {
				x: this.currentX_ + 2.0 / 3.0 * (cp.x - this.currentX_),
				y: this.currentY_ + 2.0 / 3.0 * (cp.y - this.currentY_)
			};
			var cp2 = {
				x: cp1.x + (p.x - this.currentX_) / 3.0,
				y: cp1.y + (p.y - this.currentY_) / 3.0
			};

			bezierCurveTo(this, cp1, cp2, p);
		};

		contextPrototype.arc = function(aX, aY, aRadius, aStartAngle, aEndAngle, aClockwise) {
			aRadius *= Z;
			var arcType = aClockwise ? 'at' : 'wa';

			var xStart = aX + mc(aStartAngle) * aRadius - Z2;
			var yStart = aY + ms(aStartAngle) * aRadius - Z2;

			var xEnd = aX + mc(aEndAngle) * aRadius - Z2;
			var yEnd = aY + ms(aEndAngle) * aRadius - Z2;

			// IE won't render arches drawn counter clockwise if xStart == xEnd.
			if (xStart == xEnd && !aClockwise) {
				xStart += 0.125; // Offset xStart by 1/80 of a pixel. Use something
				// that can be represented in binary
			}

			var p = this.getCoords_(aX, aY);
			var pStart = this.getCoords_(xStart, yStart);
			var pEnd = this.getCoords_(xEnd, yEnd);

			this.currentPath_.push({type: arcType,
									   x: p.x,
									   y: p.y,
									   radius: aRadius,
									   xStart: pStart.x,
									   yStart: pStart.y,
									   xEnd: pEnd.x,
									   yEnd: pEnd.y});

		};

		contextPrototype.rect = function(aX, aY, aWidth, aHeight) {
			this.moveTo(aX, aY);
			this.lineTo(aX + aWidth, aY);
			this.lineTo(aX + aWidth, aY + aHeight);
			this.lineTo(aX, aY + aHeight);
			this.closePath();
		};

		contextPrototype.strokeRect = function(aX, aY, aWidth, aHeight) {
			var oldPath = this.currentPath_;
			this.beginPath();

			this.moveTo(aX, aY);
			this.lineTo(aX + aWidth, aY);
			this.lineTo(aX + aWidth, aY + aHeight);
			this.lineTo(aX, aY + aHeight);
			this.closePath();
			this.stroke();

			this.currentPath_ = oldPath;
		};

		contextPrototype.fillRect = function(aX, aY, aWidth, aHeight) {
			var oldPath = this.currentPath_;
			this.beginPath();

			this.moveTo(aX, aY);
			this.lineTo(aX + aWidth, aY);
			this.lineTo(aX + aWidth, aY + aHeight);
			this.lineTo(aX, aY + aHeight);
			this.closePath();
			this.fill();

			this.currentPath_ = oldPath;
		};

		contextPrototype.createLinearGradient = function(aX0, aY0, aX1, aY1) {
			var gradient = new CanvasGradient_('gradient');
			gradient.x0_ = aX0;
			gradient.y0_ = aY0;
			gradient.x1_ = aX1;
			gradient.y1_ = aY1;
			return gradient;
		};

		contextPrototype.createRadialGradient = function(aX0, aY0, aR0, aX1, aY1, aR1) {
			var gradient = new CanvasGradient_('gradientradial');
			gradient.x0_ = aX0;
			gradient.y0_ = aY0;
			gradient.r0_ = aR0;
			gradient.x1_ = aX1;
			gradient.y1_ = aY1;
			gradient.r1_ = aR1;
			return gradient;
		};

		contextPrototype.drawImage = function(image, var_args) {
			var dx, dy, dw, dh, sx, sy, sw, sh;

			// to find the original width we overide the width and height
			var oldRuntimeWidth = image.runtimeStyle.width;
			var oldRuntimeHeight = image.runtimeStyle.height;
			image.runtimeStyle.width = 'auto';
			image.runtimeStyle.height = 'auto';

			// get the original size
			var w = image.width;
			var h = image.height;

			// and remove overides
			image.runtimeStyle.width = oldRuntimeWidth;
			image.runtimeStyle.height = oldRuntimeHeight;

			if (arguments.length == 3) {
				dx = arguments[1];
				dy = arguments[2];
				sx = sy = 0;
				sw = dw = w;
				sh = dh = h;
			} else if (arguments.length == 5) {
				dx = arguments[1];
				dy = arguments[2];
				dw = arguments[3];
				dh = arguments[4];
				sx = sy = 0;
				sw = w;
				sh = h;
			} else if (arguments.length == 9) {
				sx = arguments[1];
				sy = arguments[2];
				sw = arguments[3];
				sh = arguments[4];
				dx = arguments[5];
				dy = arguments[6];
				dw = arguments[7];
				dh = arguments[8];
			} else {
				throw Error('Invalid number of arguments');
			}

			var d = this.getCoords_(dx, dy);

			var w2 = sw / 2;
			var h2 = sh / 2;

			var vmlStr = [];

			var W = 10;
			var H = 10;

			// For some reason that I've now forgotten, using divs didn't work
			vmlStr.push(' <g_vml_:group',
						' coordsize="', Z * W, ',', Z * H, '"',
						' coordorigin="0,0"',
						' style="width:', W, 'px;height:', H, 'px;position:absolute;');

			// If filters are necessary (rotation exists), create them
			// filters are bog-slow, so only create them if abbsolutely necessary
			// The following check doesn't account for skews (which don't exist
			// in the canvas spec (yet) anyway.

			if (this.m_[0][0] != 1 || this.m_[0][1]) {
				var filter = [];

				// Note the 12/21 reversal
				filter.push('M11=', this.m_[0][0], ',',
							'M12=', this.m_[1][0], ',',
							'M21=', this.m_[0][1], ',',
							'M22=', this.m_[1][1], ',',
							'Dx=', mr(d.x / Z), ',',
							'Dy=', mr(d.y / Z), '');

				// Bounding box calculation (need to minimize displayed area so that
				// filters don't waste time on unused pixels.
				var max = d;
				var c2 = this.getCoords_(dx + dw, dy);
				var c3 = this.getCoords_(dx, dy + dh);
				var c4 = this.getCoords_(dx + dw, dy + dh);

				max.x = m.max(max.x, c2.x, c3.x, c4.x);
				max.y = m.max(max.y, c2.y, c3.y, c4.y);

				vmlStr.push('padding:0 ', mr(max.x / Z), 'px ', mr(max.y / Z),
							'px 0;filter:progid:DXImageTransform.Microsoft.Matrix(',
							filter.join(''), ", sizingmethod='clip');")
			} else {
				vmlStr.push('top:', mr(d.y / Z), 'px;left:', mr(d.x / Z), 'px;');
			}

			vmlStr.push(' ">',
						'<g_vml_:image src="', image.src, '"',
						' style="width:', Z * dw, 'px;',
						' height:', Z * dh, 'px;"',
						' cropleft="', sx / w, '"',
						' croptop="', sy / h, '"',
						' cropright="', (w - sx - sw) / w, '"',
						' cropbottom="', (h - sy - sh) / h, '"',
						' />',
						'</g_vml_:group>');

			this.element_.insertAdjacentHTML('BeforeEnd',
											 vmlStr.join(''));
		};

		contextPrototype.stroke = function(aFill) {
			var lineStr = [];
			var lineOpen = false;
			var a = processStyle(aFill ? this.fillStyle : this.strokeStyle);
			var color = a.color;
			var opacity = a.alpha * this.globalAlpha;

			var W = 10;
			var H = 10;

			lineStr.push('<g_vml_:shape',
						 ' filled="', !!aFill, '"',
						 ' style="position:absolute;width:', W, 'px;height:', H, 'px;"',
						 ' coordorigin="0 0" coordsize="', Z * W, ' ', Z * H, '"',
						 ' stroked="', !aFill, '"',
						 ' path="');

			var newSeq = false;
			var min = {x: null, y: null};
			var max = {x: null, y: null};

			for (var i = 0; i < this.currentPath_.length; i++) {
				var p = this.currentPath_[i];
				var c;

				switch (p.type) {
					case 'moveTo':
						c = p;
						lineStr.push(' m ', mr(p.x), ',', mr(p.y));
						break;
					case 'lineTo':
						lineStr.push(' l ', mr(p.x), ',', mr(p.y));
						break;
					case 'close':
						lineStr.push(' x ');
						p = null;
						break;
					case 'bezierCurveTo':
						lineStr.push(' c ',
									 mr(p.cp1x), ',', mr(p.cp1y), ',',
									 mr(p.cp2x), ',', mr(p.cp2y), ',',
									 mr(p.x), ',', mr(p.y));
						break;
					case 'at':
					case 'wa':
						lineStr.push(' ', p.type, ' ',
									 mr(p.x - this.arcScaleX_ * p.radius), ',',
									 mr(p.y - this.arcScaleY_ * p.radius), ' ',
									 mr(p.x + this.arcScaleX_ * p.radius), ',',
									 mr(p.y + this.arcScaleY_ * p.radius), ' ',
									 mr(p.xStart), ',', mr(p.yStart), ' ',
									 mr(p.xEnd), ',', mr(p.yEnd));
						break;
				}


				// TODO: Following is broken for curves due to
				//       move to proper paths.

				// Figure out dimensions so we can do gradient fills
				// properly
				if (p) {
					if (min.x == null || p.x < min.x) {
						min.x = p.x;
					}
					if (max.x == null || p.x > max.x) {
						max.x = p.x;
					}
					if (min.y == null || p.y < min.y) {
						min.y = p.y;
					}
					if (max.y == null || p.y > max.y) {
						max.y = p.y;
					}
				}
			}
			lineStr.push(' ">');

			if (!aFill) {
				var lineWidth = this.lineScale_ * this.lineWidth;

				// VML cannot correctly render a line if the width is less than 1px.
				// In that case, we dilute the color to make the line look thinner.
				if (lineWidth < 1) {
					opacity *= lineWidth;
				}

				lineStr.push(
						'<g_vml_:stroke',
						' opacity="', opacity, '"',
						' joinstyle="', this.lineJoin, '"',
						' miterlimit="', this.miterLimit, '"',
						' endcap="', processLineCap(this.lineCap), '"',
						' weight="', lineWidth, 'px"',
						' color="', color, '" />'
				);
			} else if (typeof this.fillStyle == 'object') {
				var fillStyle = this.fillStyle;
				var angle = 0;
				var focus = {x: 0, y: 0};

				// additional offset
				var shift = 0;
				// scale factor for offset
				var expansion = 1;

				if (fillStyle.type_ == 'gradient') {
					var x0 = fillStyle.x0_ / this.arcScaleX_;
					var y0 = fillStyle.y0_ / this.arcScaleY_;
					var x1 = fillStyle.x1_ / this.arcScaleX_;
					var y1 = fillStyle.y1_ / this.arcScaleY_;
					var p0 = this.getCoords_(x0, y0);
					var p1 = this.getCoords_(x1, y1);
					var dx = p1.x - p0.x;
					var dy = p1.y - p0.y;
					angle = Math.atan2(dx, dy) * 180 / Math.PI;

					// The angle should be a non-negative number.
					if (angle < 0) {
						angle += 360;
					}

					// Very small angles produce an unexpected result because they are
					// converted to a scientific notation string.
					if (angle < 1e-6) {
						angle = 0;
					}
				} else {
					var p0 = this.getCoords_(fillStyle.x0_, fillStyle.y0_);
					var width = max.x - min.x;
					var height = max.y - min.y;
					focus = {
						x: (p0.x - min.x) / width,
						y: (p0.y - min.y) / height
					};

					width /= this.arcScaleX_ * Z;
					height /= this.arcScaleY_ * Z;
					var dimension = m.max(width, height);
					shift = 2 * fillStyle.r0_ / dimension;
					expansion = 2 * fillStyle.r1_ / dimension - shift;
				}

				// We need to sort the color stops in ascending order by offset,
				// otherwise IE won't interpret it correctly.
				var stops = fillStyle.colors_;
				stops.sort(function(cs1, cs2) {
					return cs1.offset - cs2.offset;
				});

				var length = stops.length;
				var color1 = stops[0].color;
				var color2 = stops[length - 1].color;
				var opacity1 = stops[0].alpha * this.globalAlpha;
				var opacity2 = stops[length - 1].alpha * this.globalAlpha;

				var colors = [];
				for (var i = 0; i < length; i++) {
					var stop = stops[i];
					colors.push(stop.offset * expansion + shift + ' ' + stop.color);
				}

				// When colors attribute is used, the meanings of opacity and o:opacity2
				// are reversed.
				lineStr.push('<g_vml_:fill type="', fillStyle.type_, '"',
							 ' method="none" focus="100%"',
							 ' color="', color1, '"',
							 ' color2="', color2, '"',
							 ' colors="', colors.join(','), '"',
							 ' opacity="', opacity2, '"',
							 ' g_o_:opacity2="', opacity1, '"',
							 ' angle="', angle, '"',
							 ' focusposition="', focus.x, ',', focus.y, '" />');
			} else {
				lineStr.push('<g_vml_:fill color="', color, '" opacity="', opacity,
							 '" />');
			}

			lineStr.push('</g_vml_:shape>');

			this.element_.insertAdjacentHTML('beforeEnd', lineStr.join(''));
		};

		contextPrototype.fill = function() {
			this.stroke(true);
		}

		contextPrototype.closePath = function() {
			this.currentPath_.push({type: 'close'});
		};

		/**
		 * @private
		 */
		contextPrototype.getCoords_ = function(aX, aY) {
			var m = this.m_;
			return {
				x: Z * (aX * m[0][0] + aY * m[1][0] + m[2][0]) - Z2,
				y: Z * (aX * m[0][1] + aY * m[1][1] + m[2][1]) - Z2
			}
		};

		contextPrototype.save = function() {
			var o = {};
			copyState(this, o);
			this.aStack_.push(o);
			this.mStack_.push(this.m_);
			this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
		};

		contextPrototype.restore = function() {
			copyState(this.aStack_.pop(), this);
			this.m_ = this.mStack_.pop();
		};

		function matrixIsFinite(m) {
			for (var j = 0; j < 3; j++) {
				for (var k = 0; k < 2; k++) {
					if (!isFinite(m[j][k]) || isNaN(m[j][k])) {
						return false;
					}
				}
			}
			return true;
		}

		function setM(ctx, m, updateLineScale) {
			if (!matrixIsFinite(m)) {
				return;
			}
			ctx.m_ = m;

			if (updateLineScale) {
				// Get the line scale.
				// Determinant of this.m_ means how much the area is enlarged by the
				// transformation. So its square root can be used as a scale factor
				// for width.
				var det = m[0][0] * m[1][1] - m[0][1] * m[1][0];
				ctx.lineScale_ = sqrt(abs(det));
			}
		}

		contextPrototype.translate = function(aX, aY) {
			var m1 = [
				[1,  0,  0],
				[0,  1,  0],
				[aX, aY, 1]
			];

			setM(this, matrixMultiply(m1, this.m_), false);
		};

		contextPrototype.rotate = function(aRot) {
			var c = mc(aRot);
			var s = ms(aRot);

			var m1 = [
				[c,  s, 0],
				[-s, c, 0],
				[0,  0, 1]
			];

			setM(this, matrixMultiply(m1, this.m_), false);
		};

		contextPrototype.scale = function(aX, aY) {
			this.arcScaleX_ *= aX;
			this.arcScaleY_ *= aY;
			var m1 = [
				[aX, 0,  0],
				[0,  aY, 0],
				[0,  0,  1]
			];

			setM(this, matrixMultiply(m1, this.m_), true);
		};

		contextPrototype.transform = function(m11, m12, m21, m22, dx, dy) {
			var m1 = [
				[m11, m12, 0],
				[m21, m22, 0],
				[dx,  dy,  1]
			];

			setM(this, matrixMultiply(m1, this.m_), true);
		};

		contextPrototype.setTransform = function(m11, m12, m21, m22, dx, dy) {
			var m = [
				[m11, m12, 0],
				[m21, m22, 0],
				[dx,  dy,  1]
			];

			setM(this, m, true);
		};

		/******** STUBS ********/
		contextPrototype.clip = function() {
			// TODO: Implement
		};

		contextPrototype.arcTo = function() {
			// TODO: Implement
		};

		contextPrototype.createPattern = function() {
			return new CanvasPattern_;
		};

		// Gradient / Pattern Stubs
		function CanvasGradient_(aType) {
			this.type_ = aType;
			this.x0_ = 0;
			this.y0_ = 0;
			this.r0_ = 0;
			this.x1_ = 0;
			this.y1_ = 0;
			this.r1_ = 0;
			this.colors_ = [];
		}

		CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
			aColor = processStyle(aColor);
			this.colors_.push({offset: aOffset,
								  color: aColor.color,
								  alpha: aColor.alpha});
		};

		function CanvasPattern_() {
		}

		// set up externs
		G_vmlCanvasManager = G_vmlCanvasManager_;
		CanvasRenderingContext2D = CanvasRenderingContext2D_;
		CanvasGradient = CanvasGradient_;
		CanvasPattern = CanvasPattern_;

	})();

} // if
